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Re: FindFit and LeastSquares

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132410] Re: FindFit and LeastSquares
  • From: Costa Bravo <q13a27tt at aol.com>
  • Date: Mon, 10 Mar 2014 04:39:53 -0400 (EDT)
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  • References: <lfehp1$5lv$1@smc.vnet.net>

Alexandra Lipson wrote:
>
> data = {{1.02, .39}, {.95, .32}, {.87, .27}, {.77, .22}, {.67, .18}, {.56, \
> .15}, {.44, .13}, {.3, .12}, {.16, .13}, {.01, .15}}
>
> model = a*y^2 + b*x*y + c*x + d*y + e - x^2
> FindFit[data, model, {a, b, c, d, e}, {x, y}]
...
>
> I've been getting the error that FindFit is not a list or a rectangular
> array, among others.

FindFit  data <-> x,y,f error !!

should be
  data1 = Join[#, {0}] & /@ data
now
  w = FindFit[data1, model, {a, b, c, d, e}, {x, y}]

  out {a -> -2.6356255, b -> 0.14364618, c -> 0.55144696, d -> 3.2229403,
  e -> -0.43289427}

verification
  model1 = model /. w
(#[[3]] - (model1 /. {x -> #[[1]], y -> #[[2]]})) & /@ data1
  ListPlot[%]

-- 
  Costa




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